Stabilization of the spine is often required following trauma, tumor, or degenerative pathologies. Although each region of the spine presents unique clinical challenges, posterior fixation of the cervical spine is particularly challenging. The anatomy of the cervical spine makes it a technically challenging area to instrument. Specifically, several vital neural and vascular structures, including the vertebral arteries, nerve roots, and spinal cord, must be avoided during surgery.
Current methods of posterior cervical stabilization include the use of an occipital spinal plate and a transition rod for fixation of the cervico-thoracic junction. Such devices typically include a spinal fixation element, such as a relatively rigid fixation rod, that is coupled to adjacent vertebrae by attaching the element to various anchoring devices, such as hooks, bolts, wires, or screws. Often two rods are disposed on opposite sides of the spinous process in a substantially parallel relationship. The fixation rods can have a predetermined contour that has been designed according to the properties of the target implantation site, and once installed, the rods hold the vertebrae in a desired spatial relationship, either until healing or spinal fusion has taken place, or for some longer period of time.
It is often the case that the predetermined contour of a fixation rod does not exactly fit the contour of the implantation site. This may be attributed to various factors including a patients age, which directly relates to the size of their spinous process, irregular contouring due to disease or injury, or malformation due to a birth defect. These conditions often make it impossible to use a pre-contoured fixation rod. In these cases, multiple rods projecting at multiple angles are used, however such devices can complicate the surgery, as well as the recovery, and they can add undue strain on the spinous process, possibly resulting in an unsuccessful repair of the spine.
Accordingly, there presently exists a need for improved spinal fixation devices that can be easily installed and that allow for angular adjustment and subsequent locking. There is also a need for spinal fixation devices that have a low-profile to avoid potential irritation and injury to the patient.